The objective of the proposed research is to develop new inhibitors for tumor promotion to serve as tools in studies of the mechanism of the initiation-promotion sequence. Anti-inflammatory compounds will be studied as potential inhibitors of carcinogenesis initiated in mouse skin by 7, 12-dimethylbenz (a) anthracene (DMBA) and promoted by 12-0-tetradecanoyl-phorbol-13-acetate (TPA). Among the anti-inflammatory agents to be bioassayed are to be included nonsteroidal compounds. Phorbol 12,13-diesters will be modified by synthesis of esters potentially capable of covalent bonding with cellular macromolecules.